If /subsystem option is not specified, the linker needs to infer it from the
entry point function. If "main" or "wmain" is defined, it's a console
application. If "WinMain" or "wWinMain" is defined, it's a GUI application.
llvm-svn: 195592
The fallback atom was used only when it's searching for a symbol in a library;
if an undefined symbol was not found in a library, the LLD looked for its
fallback symbol in the library.
Although it worked in most cases, because symbols with fallbacks usually occur
only in OLDNAMES.LIB (a standard library), that behavior was incompatible with
link.exe. This patch fixes the issue so that the semantics is the same as
MSVC's link.exe
The new (and correct, I believe) behavior is this:
- If there's no definition for an undefined atom, replace the undefined atom
with its fallback and then proceed (e.g. look in the next file or stop
linking as usual.)
Weak External symbols are underspecified in the Microsoft PE/COFF spec. However,
as long as I observed the behavior of link.exe, this seems to be what we want
for compatibility.
Differential Revision: http://llvm-reviews.chandlerc.com/D2162
llvm-svn: 195269
__ImageBase is an absolute symbol whose address is the same as the image base
address. What we did before this patch was to create __ImageBase symbol as a
symbol whose *contents* (not location) is the image base address, which is
clearly wrong.
llvm-svn: 193565
Disable tests to be run with REQUIRES: disable. Note disable is not added to the
config by the test runner Mkaefiles, so essentially disables the test.
Code changes would be required to fix these tests :-
test/darwin/hello-world.objtxt
test/elf/check.test
test/elf/phdr.test
test/elf/ppc.test
test/elf/undef-from-main-dso.test
test/elf/X86_64/note-sections-ro_plus_rw.test
test/pecoff/alignment.test
test/pecoff/base-reloc.test
test/pecoff/bss-section.test
test/pecoff/drectve.test
test/pecoff/dynamic.test
test/pecoff/dynamicbase.test
test/pecoff/entry.test
test/pecoff/hello.test
test/pecoff/imagebase.test
test/pecoff/importlib.test
test/pecoff/lib.test
test/pecoff/multi.test
test/pecoff/reloc.test
test/pecoff/weak-external.test
llvm-svn: 193300
We should dead-strip atoms only if they are created for COMDAT symbols. If we
remove non-COMDAT atoms from a binary, it will no longer be guaranteed that
the binary will work correctly.
In COFF, you can manipulate the order of section contents in the resulting
binary by section name. For example, if you have four sections
.data$unique_prefix_{a,b,c,d}, it's guaranteed that the contents of A, B, C,
and D will be consecutive in the resulting .data section in that order.
Thus, you can access B's and C's contents by incrementing a pointer pointing
to A until it reached to D. That's why we cannot dead-strip B or C even if
no one is directly referencing to them.
Some object files in the standard library actually use that technique.
llvm-svn: 193017
Dead-strip root symbols can be undefined atoms, but should not really be
nonexistent, because dead-strip root symbols should be added to initial
undefined atoms at startup. Whenever you look up its name in the symbol
table, some type of atom will always exist.
llvm-svn: 192831
-- so that command line options to specify new input files, such as
/defaultlib:foo, is handled properly. Such options were ignored before
this patch.
llvm-svn: 192342
We used to support both Windows and Unix style command line options. In Windows
style, an option and its value are separated by ":" (colon). In Unix, separator
is a space. Accepting both styles were convenient, but we can no longer allow
Unix style because I found that can be ambiguous.
For example, /nodefaultlib option takes an optional argument. In Windows style
it's going to be something like "/nodefaultlib:foo". There's no ambiguity what
"foo" means. However, if the option is "/nodefaultlib foo", "foo" can be
interpreted either an optional argument for "/nodefaultlib" or an input file
"foo.obj". We should just stop accepting the non-standard command line style.
llvm-svn: 191247
Summary:
This patch changes WriterPECOFF to actually write down the address instead of ignoring it.
Also, it changes the order of adding the BaseReloc chunk as otherwise the address wasn't set yet.
I think a better way of doing it would be to change DataDirectoryAtom to create a Reference
instead of using a number, and to change IdataPass accordingly, but I'm not sure how to do that.
Reviewers: ruiu
Reviewed By: ruiu
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1743
llvm-svn: 191220
Summary: This patch changes WritePECOFF to calculate the value of the SizeOfHeaders PE header field instead of just using 512.
Reviewers: rui314, ruiu
Reviewed By: ruiu
CC: llvm-commits, ruiu
Differential Revision: http://llvm-reviews.chandlerc.com/D1708
llvm-svn: 191212
This patch changes lld to go through all sections while calculating the size
for SizeOfCode, SizeOfInitializedData and SizeOfUninitializedData fields in the
PE header, instead of using only a small set of hard-coded sections.
This only really changes SizeOfInitializedData which didn't include .reloc
section before this patch.
Patch by Ron Ofir.
llvm-svn: 190799
This patch sets the IMAGE_SCN_MEM_DISCARDABLE characteristic to the base
relocations section in order to match MS PECOFF specification.
Patch by Ron Ofir.
llvm-svn: 190798
There was a bug that if a section has an alignment requirement and there are
multiple symbols at offset 0 in the section, only the last atom at offset 0
would be aligned properly. That bug would move only the last symbol to an
alignment boundary, leaving other symbols unaligned, although they should be at
the same location. That caused a mysterious SEGV error of the resultant
executable.
With this patch, we manage all symbols at the same location properly, rather
than keeping the last one.
llvm-svn: 190724
We need to order atoms that exist in the same chain. This is to make sure that
the command line order is preserved when we emit the atoms to the output file.
Credits: BigCheese for finding the bug.
Adds a test which otherwise would fail.
llvm-svn: 190608
The compiler is allowed to add a linker option starting with -?<name> to
.drectve section. If the linker can interpret -<name>, it's processed as if
there's no question mark there. If not, such option is silently ignored.
This is a COFF's feature to allow the compiler to emit new linker options
while keeping compatibility with older linkers.
llvm-svn: 189897
This adds an API to the LinkingContext for flavors to add Internal files
containing atoms that need to appear in the YAML output as well, when -emit-yaml
switch is used.
Flavors can add more internal files for other options that are needed.
llvm-svn: 189718
We added layout edges to the head atoms in grouped sections. That was wrong,
because the head atom needs to be followed by the other atoms in the *same*
section, not by the other section contents. With this patch, layout edges are
added from tail atom, which is the last atom in a section, to head atom.
llvm-svn: 189573
Because of a bug, the last atom of each section contained a garbage at the
end of its data. In most cases the garbage is harmless but it could have cause
SEGV.
llvm-svn: 189572
With this patch the entry symbol is treated as an undefined symbol, to force
the resolver to resolve the entry symbol.
Differential Revision: http://llvm-reviews.chandlerc.com/D1524
llvm-svn: 189307
The import name is not always the same as the symbol name. If the name/type
field in the import header is NOPREFIX or UNDECORATE, we need to strip some
characters from symbol to get its import name.
The Microsoft PE/COFF spec is vague if symbol contains more than two
consecutive characters to be stripped. We used to strip all characters,
but it doesn't seem right as we couldn't link against the system library
because of this name mangling. Looks like we shouldn't strip more than one
character.
llvm-svn: 188154
__ImageBase is a symbol having 4 byte integer equal to the image base address
of the resultant executable. The linker is expected to create the symbol as if
it were read from a file.
In order to emit the symbol contents only when the symbol is actually
referenced, we created a pseudo library file to wrap the linker generated
symbol. The library file member is emitted to the output only when the member
is actually referenced, which is suitable for our purpose.
llvm-svn: 188052
The COMDAT section is a section with a special attribute to tell the linker
whether the symbols in the section are allowed to be merged or not. This patch
add a function to interpret the COMDAT data and set "merge" attribute to the
atoms accordingly.
LLD supports multiple policies to merge atoms; atoms can be merged by name or
by content. COFF supports them, and in addition to that, it supports
choose-the-largest-atom policy, which LLD currently does not support. I simply
mapped it to merge-by-name attribute for now, but we eventually have to support
that policy in the core linker.
llvm-svn: 188025
Summary:
The .drectve section contains linker command line options, and the linker is
expected to interpret them as if they were given via the command line. In this
patch, the command line parser in the driver is called from the object file
reader to parse the string.
I think this patch is important, because this is the first step towards mutable
TargetInfo. We had a discussion about that on llvm-commits mailing list before.
I haven't removed "const" from the function signature yet. Instead, I just use
cast to remove "const". This is a temporary aid for an experiment. If we don't
see any issue with this mutable TargetInfo appraoch, I'll change the function
signature, and rename the class LinkerContext from TargetInfo.
Reviewers: kledzik
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1246
llvm-svn: 187677
This patch removes hacky mangle() function, which strips all decorations
uncondtitionally. LLD now interprets Import Name/Type field in the import
library properly as described in the Microsoft PE/COFF Spec.
llvm-svn: 187388
Some sections, such as with IMAGE_SCN_LNK_REMOVE attribute, is skipped
in the first pass. Such sections need to be skipped in the latter passes.
llvm-svn: 187281
The /include command line option is equivalent to Unix --undefined
option, which forces the linker to resolve the given symbol name
as if it's an unresolved symbol in one of its input files. This feature
is used to link an additional object file or a shared library that no
input files refer to.
llvm-svn: 187084
Emit .reloc section. This is the first step to support DLL creation. The
executable doesn't need .reloc section, but the DLL does.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1126
llvm-svn: 186336
This patch adds a new pass, IdataPass, to transform shared atom references
to real references and to construct the .idata section data. With this patch
lld can produce a working Hello World program by linking it against
kernel32.dll and user32.dll.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1096
llvm-svn: 186071
This is the first patch toward full DLL support. With this patch, lld can
read .lib file for a DLL.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D987
llvm-svn: 184101
With this patch, it can now resolve relocations in the same output file.
"Hello world" program does not still work because call to the DLL routine
is not supported yet.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D985
llvm-svn: 184063
Archive file in Windows has file extension of ".lib" but the file format is
in fact the same as Unix. It's an ar archive holding multiple .obj files.
The existing archive reader can read .lib files.
llvm-svn: 184036
Summary:
COFFReference class is defined to represent relocation information for
COFFDefinedAtom, as ELFReference for ELFDefinedAtom. ReaderCOFF can now
read relocation entries and create COFFReferences accordingly.
I need to make WriterPECOFF to handle the relocation references created by
the reader, but this patch is already big, so I think it's probably better
to get it reviewed now.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D976
llvm-svn: 183964
lld can now output a valid Windows executable with a text section that does nothing
but just returns immediately. It's not able to handle relocations, symbol tables,
data sections, etc, so it still can't do anything practical, though.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D892
llvm-svn: 183478
Add WinLinkDriver and connect it to the existing COFF reader. Remaining
parts are still stubs, so while it can now read a COFF file, it still
cannot link or output PE/COFF files yet.
Reviewers: Bigcheese
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D865
llvm-svn: 182784
Rui Ueyama